as most workflows needs some settings (as api key etc) mostly workflow creators implement it through alfredd search, which is not convenient at all.
The option to add settings to workflow will improve it by a lot and will make it easier to use.
When user "install" workflow, a screen with setting will be pop up.
Whenever user want to change the settings after, the option can be thorough the alfredapp search by typing: <workflow_name>:settings (or something similar) or by right click on the workflow.
It will be best if settings for stuff like OAUTH will be implemented as an option for the developers, but a key/val should be good enough for a start.